Android Volley Null Pointer Exception

Question

I'm attempting to convert a previously Activity-based tutorial to a Fragment, but I continue to run into the NullPointerException error on my Adapter.

The tutorial is based on this and I have slimmed down the constructor for the Adapter because it used to be calling an Activity.

There is one possible solution here but nobody knows how to proceed with the same possible question.

I want to convert everything to a working Fragment. Please let me know if you need more information from me.

Main converted class:

public class mainViewController2 extends Fragment {
    private static final String TAG = mainViewController2.class.getSimpleName();
    private ListView listView;
    private FeedListAdapter listAdapter;
    private List<FeedItem> feedItems;
    private String URL_FEED = "http://api.androidhive.info/feed/feed.json";

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                    Bundle savedInstanceState) {

        View v = inflater.inflate(R.layout.mainviewcontroller2_fragment, container, false);

        listView = (ListView) v.findViewById(R.id.list);

        feedItems = new ArrayList<FeedItem>();


        //where the error shows up?
        listAdapter = new FeedListAdapter(feedItems);
        listView.setAdapter(listAdapter);



        // We first check for cached request
        Cache cache = AppController.getInstance().getRequestQueue().getCache();
        Entry entry = cache.get(URL_FEED);
        if (entry != null) {
            // fetch the data from cache
            try {
                String data = new String(entry.data, "UTF-8");
                try {
                    parseJsonFeed(new JSONObject(data));
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }

        } else {
            // making fresh volley request and getting json
            JsonObjectRequest jsonReq = new JsonObjectRequest(Method.GET,
                    URL_FEED, null, new Response.Listener<JSONObject>() {

                        @Override
                        public void onResponse(JSONObject response) {
                            VolleyLog.d(TAG, "Response: " + response.toString());
                            if (response != null) {
                                parseJsonFeed(response);
                            }
                        }
                    }, new Response.ErrorListener() {

                        @Override
                        public void onErrorResponse(VolleyError error) {
                            VolleyLog.d(TAG, "Error: " + error.getMessage());
                        }
                    });

            // Adding request to volley request queue
            AppController.getInstance().addToRequestQueue(jsonReq);
        }

        return v;
    }

    /**
     * Parsing json reponse and passing the data to feed view list adapter
     * */
    private void parseJsonFeed(JSONObject response) {
        try {
            JSONArray feedArray = response.getJSONArray("feed");

            for (int i = 0; i < feedArray.length(); i++) {
                JSONObject feedObj = (JSONObject) feedArray.get(i);

                FeedItem item = new FeedItem();
                item.setId(feedObj.getInt("id"));
                item.setName(feedObj.getString("name"));

                // Image might be null sometimes
                String image = feedObj.isNull("image") ? null : feedObj
                        .getString("image");
                item.setImge(image);
                item.setStatus(feedObj.getString("status"));
                item.setProfilePic(feedObj.getString("profilePic"));
                item.setTimeStamp(feedObj.getString("timeStamp"));

                // url might be null sometimes
                String feedUrl = feedObj.isNull("url") ? null : feedObj
                        .getString("url");
                item.setUrl(feedUrl);

                feedItems.add(item);
            }

            // notify data changes to list adapater
            listAdapter.notifyDataSetChanged();
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }
}

FeedListAdapter:

 public class FeedListAdapter extends BaseAdapter { 
    private Activity activity;
    private LayoutInflater inflater;
    private List<FeedItem> feedItems;

    Context context;

    ImageLoader imageLoader;

     public FeedListAdapter(Context ctx,List<FeedItem> feedItems) {
        this.context= ctx;
        this.feedItems = feedItems;
        imageLoader = AppController.getInstance().getImageLoader();
        inflater = LayoutInflater.from(context);
     }

    @Override
    public int getCount() {
        return feedItems.size();
    }

    @Override
    public Object getItem(int location) {
        return feedItems.get(location);
    }
        @Override
        public long getItemId(int position) {
            return position;
        }

        @SuppressLint("InflateParams")
        @Override
        public View getView(int position, View convertView, ViewGroup parent) {

            if (inflater == null)
                inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            if (convertView == null)
                convertView = inflater.inflate(R.layout.feed_item, null);

            if (imageLoader == null)
                imageLoader = AppController.getInstance().getImageLoader();

            TextView name = (TextView) convertView.findViewById(R.id.name);
            TextView timestamp = (TextView) convertView
                    .findViewById(R.id.timestamp);
            TextView statusMsg = (TextView) convertView
                    .findViewById(R.id.txtStatusMsg);
            TextView url = (TextView) convertView.findViewById(R.id.txtUrl);
            NetworkImageView profilePic = (NetworkImageView) convertView
                    .findViewById(R.id.profilePic);
            FeedImageView feedImageView = (FeedImageView) convertView
                    .findViewById(R.id.feedImage1);

            FeedItem item = feedItems.get(position);

            name.setText(item.getName());

            // Converting timestamp into x ago format
            CharSequence timeAgo = DateUtils.getRelativeTimeSpanString(
                    Long.parseLong(item.getTimeStamp()),
                    System.currentTimeMillis(), DateUtils.SECOND_IN_MILLIS);
            timestamp.setText(timeAgo);

            // Chcek for empty status message
            if (!TextUtils.isEmpty(item.getStatus())) {
                statusMsg.setText(item.getStatus());
                statusMsg.setVisibility(View.VISIBLE);
            } else {
                // status is empty, remove from view
                statusMsg.setVisibility(View.GONE);
            }

            // Checking for null feed url
            if (item.getUrl() != null) {
                url.setText(Html.fromHtml("<a href=\"" + item.getUrl() + "\">"
                        + item.getUrl() + "</a> "));

                // Making url clickable
                url.setMovementMethod(LinkMovementMethod.getInstance());
                url.setVisibility(View.VISIBLE);
            } else {
                // url is null, remove from the view
                url.setVisibility(View.GONE);
            }

            // user profile pic
            profilePic.setImageUrl(item.getProfilePic(), imageLoader);

            // Feed image
            if (item.getImge() != null) {
                feedImageView.setImageUrl(item.getImge(), imageLoader);
                feedImageView.setVisibility(View.VISIBLE);
                feedImageView
                        .setResponseObserver(new FeedImageView.ResponseObserver() {
                            @Override
                            public void onError() {
                            }

                            @Override
                            public void onSuccess() {
                            }
                        });
            } else {
                feedImageView.setVisibility(View.GONE);
            }

            return convertView;
        }

    }

LogCat errors:

09-06 02:51:55.823: E/AndroidRuntime(8279): FATAL EXCEPTION: main
09-06 02:51:55.823: E/AndroidRuntime(8279): Process: com.rynovation.kline, PID: 8279
09-06 02:51:55.823: E/AndroidRuntime(8279): java.lang.NullPointerException
09-06 02:51:55.823: E/AndroidRuntime(8279):     at androidFeedClasses.FeedListAdapter.<init>(FeedListAdapter.java:35)
09-06 02:51:55.823: E/AndroidRuntime(8279):     at com.rynovation.kline.mainViewController2.onCreateView(mainViewController2.java:51)
09-06 02:51:55.823: E/AndroidRuntime(8279):     at android.app.Fragment.performCreateView(Fragment.java:1700)
09-06 02:51:55.823: E/AndroidRuntime(8279):     at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:890)
09-06 02:51:55.823: E/AndroidRuntime(8279):     at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1062)
09-06 02:51:55.823: E/AndroidRuntime(8279):     at android.app.BackStackRecord.run(BackStackRecord.java:684)
09-06 02:51:55.823: E/AndroidRuntime(8279):     at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1453)
09-06 02:51:55.823: E/AndroidRuntime(8279):     at android.app.FragmentManagerImpl$1.run(FragmentManager.java:443)
09-06 02:51:55.823: E/AndroidRuntime(8279):     at android.os.Handler.handleCallback(Handler.java:733)
09-06 02:51:55.823: E/AndroidRuntime(8279):     at android.os.Handler.dispatchMessage(Handler.java:95)
09-06 02:51:55.823: E/AndroidRuntime(8279):     at android.os.Looper.loop(Looper.java:146)
09-06 02:51:55.823: E/AndroidRuntime(8279):     at android.app.ActivityThread.main(ActivityThread.java:5487)
09-06 02:51:55.823: E/AndroidRuntime(8279):     at java.lang.reflect.Method.invokeNative(Native Method)
09-06 02:51:55.823: E/AndroidRuntime(8279):     at java.lang.reflect.Method.invoke(Method.java:515)
09-06 02:51:55.823: E/AndroidRuntime(8279):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
09-06 02:51:55.823: E/AndroidRuntime(8279):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
09-06 02:51:55.823: E/AndroidRuntime(8279):     at dalvik.system.NativeStart.main(Native Method)

Your adapter is all over the place. Read about the ViewHolder pattern and try to create something similar. Here's the google version but try searching for examples as well: http://developer.android.com/training/improving-layouts/smooth-scrolling.html — Itai Hanski, Sep 12 '14 at 01:17

score 27 · Answer 1 · edited Jul 11 '16 at 12:26

27

I guess you missed a simple code in your manifest file. Your AppController package extends Application , So the application tag in your manifest is searching for the AppController but isn't able to find.

Just Write this simple code in your AndroidManifest.xml

android:name = your.package.AppController

edited Jul 11 '16 at 12:26

Shashanth

4,995
7
41
51

answered Oct 14 '14 at 05:52

user3902144

291
2
7

1

sir, you are time saver. – Murat Dec 23 '15 at 21:52

score 11 · Answer 2 · edited May 23 '17 at 12:25

11

A little late maybe, but a representative answer to user3902144's answer:

Similar Answer to this question : Link

You may have missed out this from your manifest:

 <application
        android:name="<package-name>.app.AppController" // <-- this one
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme">

That's why onCreate never called and mInstance is null.

Hope this helps :)

edited May 23 '17 at 12:25

Community

1
1

answered Dec 02 '14 at 13:39

David Passmore

6,089
4
46
70

Thanks! Never too late haha – CodeGuru May 10 '15 at 01:12
too late answer helped me :-) – Ranjithkumar Jun 23 '15 at 03:20
If you can't because have multidex ? – Dec 07 '15 at 15:03
@delive can you elaborate? – David Passmore Dec 23 '15 at 20:43

score 1 · Answer 3 · answered Sep 06 '14 at 06:08

1

Looking at the error, it seems like you're calling getActivity() inside onCreateView(). You should be getting the activity in onActivityCreated instead where it shouldn't be null.

answered Sep 06 '14 at 06:08

bph

189
2
14

What do you suggest I do? It's meant to be a Fragment, not an Activity. Can you please write an example if possible? – user2793987 Sep 06 '14 at 06:12
Can you explain why you need to reach into the activity to find the list view? Is the listview not inside R.layout.mainviewcontroller2_fragment? – bph Sep 06 '14 at 06:17
Where's the constructor for FeedListAdapter that only takes in one argument: `new FeedListAdapter(feedItems);`? I'm only seeing `public FeedListAdapter(Context ctx,List feedItems)` – bph Sep 06 '14 at 22:20
It apparently doesn't exist. Any ideas of what it should look like? – user2793987 Sep 07 '14 at 03:13
Can you click on it to go to the method declaration? It should exist somewhere. Otherwise, your code wouldn't compile. – bph Sep 07 '14 at 07:54
It goes to the same FeedListAdapter, there isn't a specific one that allows for one argument in the constructor. – user2793987 Sep 07 '14 at 08:06
What's line 35 inside FeedListAdapter? – bph Sep 08 '14 at 01:08

Piyush · Answer 4 · 2014-09-06T06:38:01.513

1

Change this from

listView = (ListView) getActivity().findViewById(R.id.list);

to

listView = (ListView)v.findViewById(R.id.list);

This is because getActivity() is generally used for as a Context in Fragment. While you'r find id for your UI elements in Fragment then you have to give reference of your View's object which will be returned in onCreateView() method.

Update:

Change your Adapter Like,

listAdapter = new FeedListAdapter(getActivity(),feedItems);

Now in its Constructor

 ImageLoader imageLoader;

 public FeedListAdapter(Context ctx,List<FeedItem> feedItems) {
    this.context= ctx;
    this.feedItems = feedItems;
    imageLoader = AppController.getInstance().getImageLoader()
 }

Now in your adapter class use context variable as a Context.

edited Sep 06 '14 at 06:38

answered Sep 06 '14 at 06:18

Piyush

18,895
5
32
63

Thanks, but I still get the same error. I think this may be caused in the FeedListAdapter? – user2793987 Sep 06 '14 at 06:34
Ok, I updated my post as well to reflect your changes. However, the problem now seems to be in the constructor. See updated logcat above please. – user2793987 Sep 06 '14 at 06:48
add this line inflater = LayoutInflater.from(context) to your adapter constructor – Piyush Sep 06 '14 at 06:49
Ok, well I did that and now I'm getting an error pointing there via the new logcat/updated code. See above. – user2793987 Sep 06 '14 at 06:54
Any ideas left? I did exactly what you said and still the same error is showing up. – user2793987 Sep 06 '14 at 18:29

score 0 · Answer 5 · answered Feb 28 '17 at 03:32

Please check all your params carefully, make sure not to send any null value in params, if using some stored values then use the condition like below:

@Override
protected Map<String, String> getParams() {
 Map<String, String> params = new HashMap<String, String>();
 if(paramValue!= null)
     params.put("paramKey", paramValue);
  else
     params.put("paramKey", "anyOtherDefaultValue");
 return params;
 }

score 0 · Answer 6 · answered Apr 03 '21 at 17:08

0

//I was Stack in This Error and I solved this just by Writing this in your AppController Class.

@Override
    public void onCreate() {
        super.onCreate();
        instance = this;
    }
}

answered Apr 03 '21 at 17:08

Mushahid Hussain

1

Android Volley Null Pointer Exception

6 Answers6